This invention relates to polymer foams from hydrogenated vinyl aromatic polymers.
Polystyrene insulation foam and polyethylene packaging foams are made in commercial quantities using an extrusion process. However, commercial extrusion processes are not easily adapted for use with a wide variety of polymers. Thus, although polystyrene, LDPE (low density polyethylene made in a high pressure process) and some grades of polypropylene are readily processed through an extrusion process, many other common polymers, notably LLDPE (linear low density polyethylene) and HDPE (high density polyethylene), can be extruded into foam with difficulty, if at all. Additionally, these foams have insufficient heat resistance for many applications, such as adiabatic thermal insulation and other applications requiring heat resistance at polymer softening temperatures.
JP-03234741 of Hitachi discloses bead expansion molding (bead stock foam) of a polyvinylcyclohexane resin, having good heat resistance and weatherability. The polymers disclosed include vinylcyclohexane homopolymer and copolymers thereof with fatty acid esters, cyanovinyl compounds, unsaturated dibasic acids, or unsaturated fatty acids.
It remains desirable to obtain other types of foams from hydrogenated aromatic polymers and foams from other copolymers of hydrogenated aromatic polymers.